Lubricating Composition Containing a Dispersant

ABSTRACT

The invention provides a lubricating composition containing a lubricating composition comprising an oil of lubricating viscosity and a polyester. The invention further relates to a method of lubricating a mechanical device (such as an internal combustion engine) with the lubricating composition. The invention further relates to the use of the polyester as a dispersant.

FIELD OF INVENTION

The invention provides a lubricating composition containing alubricating composition comprising an oil of lubricating viscosity and apolyester. The invention further relates to a method of lubricating amechanical device (such as an internal combustion engine) with thelubricating composition. The invention further relates to the use of thepolyester as a dispersant.

BACKGROUND OF THE INVENTION

In order to reduce deposit formation, detergents and dispersants areknown to assist in maintaining reduced amounts of deposits on enginecomponents. The lubricant industry has a number of tests used toevaluate a lubricant's ability to handle deposits and sludge includingthe Sequence VG, Sequence IIIG, TDi, Cat 1N, and OM501LA.

With recent changes to engine specifications there is an increasingdemand on the lubricant to reduce deposits. For instance, the new ILSACGF-5 specification requires a 4.0 weighted piston deposit rating in theSequence IIIG (vs. 3.5 for GF-4).

International Application WO2007/128740 (published 15 Nov., 2007)discloses the use of one or more poly (hydroxycarboxylic acid) amidesalt in combination with one or more antiwear additive. Suchcompositions were useful for dispersing preformed sludge deposits.

International Application WO2009/053413 (published 30 Apr. 2009) andEuropean Patent Application EP2055729 (published 6 May 2009) bothdisclose compositions comprising base oil and one or more poly(hydroxycarboxylic acid) amide salt derivatives. The lubricating oilswere useful for reducing wear and friction.

International Application WO2009/156393 (published 30 Dec. 2009)discloses a lubricant with one or more poly (hydroxycarboxylic acid)amide salt with TBN less than 10. The Lubricant ameliorated pistondeposits in fired engine tests such as the TU5 and Sequence IIIF.

International Application WO2010/012756 (published 4 Feb. 2010) and USPatent Application US2010/0024286 (published 4 Feb. 2010) both disclosea fuel composition comprising a fuel and one or more poly(hydroxycarboxylic acid) amide salts. Such fuels offered benefits suchas improved lubricity by HFRR, Improved inlet valve deposits in firedengine tests and improved sludge dispersancy in the Sequence VG enginetest.

International Application WO2010/014678 (published 4 Feb. 2010)discloses a poly (hydroxycarboxylic acid) amide salt derivative whereinthe anionic portion of the salt does not contain sulphur. The moleculesdescribed showed lower phosphorus volatility in Selby NOACK testing infully formulated fluids than similar materials that hadsulphur-containing anions.

International Application WO2010/015706 (published 11 Feb. 2010)discloses a lubricant comprising base oil, a poly (hydroxycarboxylicacid) amide salt and one or more detergents. The composition is usefulfor dispersing preformed sludge deposits.

International Application WO2010/012763 (published 4 Feb. 2010) and USPatent Application US2010/0024287 (published 4 Feb. 2010) both disclosea fuel composition comprising a fuel and one or more poly(hydroxycarboxylic acid) derivative having a terminal acid group. Thefuels of the disclosed composition demonstrated some improved lubricitycharacteristics.

SUMMARY OF THE INVENTION

The objectives of the present invention include providing at least oneof (i) dispersancy, (ii) cleanliness, or (iii) a lubricant with reducedsludge deposit formation.

As used herein reference to the amounts of additives present in thelubricating composition disclosed are quoted on an oil free basis, i.e.,amount of actives, unless otherwise indicated.

In one embodiment the present invention provides a lubricatingcomposition comprising an oil of lubricating viscosity and 0.05 wt % to10 wt % of a polyester which comprises a self-condensation product of aC₈₋₂₂ (or C₁₀₋₂₀) fatty carboxylic acid containing at least one hydroxylgroup.

The self-condensation product of the C₈₋₂₂ (or C₁₀₋₂₀) fatty carboxylicacid containing at least one hydroxyl group may produce a polyestercomprising 2 to 10, or 2 to 8, or 3 to 6 repeat units of said acid.

In one embodiment the present invention provides a lubricatingcomposition comprising a dispersant (typically a succinimidedispersant), an oil of lubricating viscosity and a 0.05 wt % to 10 wt %of a polyester which comprises a self-condensation product of a C₈₋₂₂(or C₁₀₋₂₀) fatty carboxylic acid containing at least one hydroxylgroup.

In one embodiment the present invention provides a lubricatingcomposition comprising:

an oil of lubricating viscosity;0.1 wt % to 10 wt %, or 1 wt % to 8 wt % of a polyester which comprisesa self-condensation product of a C₈₋₂₂ (or C₁₀₋₂₀) fatty carboxylic acidcontaining at least one hydroxyl group; and0.1 wt % to 15 wt %, or 0.5 wt % to 9 wt % of a dispersant (typically asuccinimide dispersant).

In one embodiment the present invention provides a lubricatingcomposition comprising:

an oil of lubricating viscosity;1 wt % to 6.5 wt % of a polyester which comprises a self-condensationproduct of a C₈₋₂₂ (or C₁₀₋₂₀) fatty carboxylic acid containing at leastone hydroxyl group; and2 wt % to 8.5 wt % of a dispersant (typically a succinimide dispersant).

In one embodiment the invention provides for a method of lubricating amechanical device with a lubricating composition disclosed herein. Themechanical device may be an internal combustion engine.

The internal combustion engine may have a steel surface on at least oneof a cylinder bore, cylinder block, or piston ring.

The internal combustion engine may have an aluminium alloy, or aluminiumcomposite surface on at least one of a cylinder bore, cylinder block, orpiston ring.

In one embodiment the invention provides for the use of the polyester ofthe invention as a dispersant in a lubricant for use in an internalcombustion engine.

DETAILED DESCRIPTION OF THE INVENTION

The present invention provides a detergent, a process to prepare adetergent/dispersant, a lubricating composition, a method forlubricating a mechanical device and a use as disclosed above.

The Polyester

As used herein the term “fatty carboxylic acid” used in relation to thepolyester means an acid with a carbon chain of 8 to 22, or 10 to 22carbon atoms.

As used herein the term “polyester” is intended to include a polymer inwhich the monomer units are linked together by a group —C(O)O—.

The C₈₋₂₂ (or C₁₀₋₂₀) fatty carboxylic acid containing at least onehydroxyl group from which the polyester of the present invention may beprepared include a compound represented by the formula:

wherein R¹ may be a hydrogen or a hydrocarbyl group containing from 1 to20 carbon atoms and R² may be a hydrocarbylene group containing from 1to 20 carbon atoms, with the proviso that the total number of carbonatoms present from R¹ and R² may be 6 or more, or 8 or more. In someembodiments R¹ contains from 1 to 12, 2 to 10, 4 to 8 or even 6 carbonatoms R² may contain from 2 to 16, 6 to 14, 8 to 12, or even 10 carbonatoms.

In some embodiments the fatty carboxylic acid used in the preparation ofthe polyester may be 12-hydroxystearic acid, ricinoleic acid, 12-hydroxydodecanoic acid, 5-hydroxy dodecanoic acid, 5-hydroxy decanoic acid,4-hydroxy decanoic acid, 10-hydroxy undecanoic acid, or combinationsthereof.

In one embodiment the fatty carboxylic acid used in the preparation ofthe polyester may be 12-hydroxystearic acid. In one embodiment the fattycarboxylic acid used in the preparation of the polyester may bericinoleic acid.

In these embodiments the polyester may (or may not) be capped with aC1-22, or a C8-20, fatty acid. Examples of suitable acids include oleicacid, palmitic acid, stearic acid, erucic acid, lauric acid,2-ethylhexanoic acid, 9,11-linoleic acid, 9,12-linoleic acid,9,12,15-linolenic acid, abietic acid, or combinations thereof.

The number average molecular weight (Mn) of the polyesters of theinvention may be from 500 to 3000, or from 700 to 2500.

The polyester useful in the present invention may be obtained/obtainableby heating one or more hydroxycarboxylic acids or a mixture of thehydroxycarboxylic acid and a carboxylic acid, optionally in the presenceof an esterification catalyst. The hydroxycarboxylic acids may, incertain embodiments, have the formula HO—X—COOH wherein X may be adivalent saturated or unsaturated aliphatic radical containing at least8 carbon atoms and in which there are at least 4 carbon atoms betweenthe hydroxy and carboxylic acid groups, or from a mixture of such ahydroxycarboxylic acid and a carboxylic acid which is free from hydroxygroups. This reaction may be carried out at a temperature in the regionof 160° C. to 200° C., until the desired molecular weight has beenobtained. The course of the esterification may be followed by measuringthe acid value of the product, with the desired polyester, in someembodiments, having an acid value in the range of 10 to 100 mg KOH/g orin the range of 20 to 50 mg KOH/g. The indicated acid value range of 10to 100 mg KOH/g is equivalent to a number average molecular weight rangeof 5600 to 560. The water formed in the esterification reaction may beremoved from the reaction medium, and this may be conveniently done bypassing a stream of nitrogen over the reaction mixture or by carryingout the reaction in the presence of a solvent, such as toluene orxylene, and distilling off the water as it is formed.

The resulting polyester may then be isolated in conventional manner;however, when the reaction is carried out in the presence of an organicsolvent whose presence would not be harmful in the subsequentapplication, the resulting solution of the polyester may be used.

In the said hydroxycarboxylic acids the radical represented by X maycontain from 12 to 20 carbon atoms, optionally where there are between 8and 14 carbon atoms between the carboxylic acid and hydroxy groups. Insome embodiments the hydroxycarboxylic acid may contain a second hydroxygroup. Typically, the hydroxycarboxylic acid may contain one hydroxygroup and one carboxylic acid group.

Specific examples of such hydroxycarboxylic acids include ricinoleicacid, a mixture of 9- and 10-hydroxystearic acids (obtained bysulphation of oleic acid followed by hydrolysis), and 12-hydroxystearicacid, and especially the commercially available hydrogenated castor oilfatty acid which contains in addition to 12-hydroxystearic acid minoramounts of stearic acid and palmitic acid.

The carboxylic acids which may be used in conjunction with thehydroxycarboxylic acids to obtain these polyesters are preferablycarboxylic acids of saturated or unsaturated aliphatic compounds,particularly alkyl and alkenyl carboxylic acids containing a chain offrom 8 to 20 carbon atoms. As examples of such acids there may bementioned lauric acid, palmitic acid, stearic acid and oleic acid.

In one embodiment the polyester may be derived from commercial12-hydroxy-stearic acid and may have a number average molecular weightof about 1600. Polyesters such as this are described in greater detailin U.K. Patent Specification Nos. 1373660 and 1342746.

In certain embodiments the polyester may be present at 0.1 wt % to 10 wt%, or 1 wt % to 8 wt %, or 2 wt % to 6.5 wt % of the lubricatingcomposition.

Dispersant

The lubricating composition may further include a dispersant, ormixtures thereof. The dispersant may be a succinimide dispersant, aMannich dispersant, a succinamide dispersant, a polyolefin succinic acidester, amide, or ester-amide, or mixtures thereof. In one embodiment theinvention does include a dispersant or mixtures thereof. The dispersantmay be present as a single dispersant. The dispersant may be present asa mixture of two or more (typically two or three) different dispersants,wherein at least one may be a succinimide dispersant.

The succinimide dispersant may be derived from an aliphatic polyamine,or mixtures thereof. The aliphatic polyamine may be aliphatic polyaminesuch as an ethylenepolyamine, a propylenepolyamine, a butylenepolyamine,or mixtures thereof. In one embodiment the aliphatic polyamine may beethylenepolyamine. In one embodiment the aliphatic polyamine may beselected from the group consisting of ethylenediamine,diethylenetriamine, triethylenetetramine, tetraethylenepentamine,pentaethylenehexamine, polyamine still bottoms, and mixtures thereof.

In one embodiment the dispersant may be a polyolefin succinic acidester, amide, or ester-amide. For instance, a polyolefin succinic acidester may be a polyisobutylene succinic acid ester of pentaerythritol,or mixtures thereof. A polyolefin succinic acid ester-amide may be apolyisobutylene succinic acid reacted with an alcohol (such aspentaerythritol) and an amine (such as a diamine, typicallydiethyleneamine).

The dispersant may be an N-substituted long chain alkenyl succinimide.An example of an N-substituted long chain alkenyl succinimide ispolyisobutylene succinimide. Typically the polyisobutylene from whichpolyisobutylene succinic anhydride is derived has a number averagemolecular weight of 350 to 5000, or 550 to 3000 or 750 to 2500.Succinimide dispersants and their preparation are disclosed, forinstance in U.S. Pat. Nos. 3,172,892, 3,219,666, 3,316,177, 3,340,281,3,351,552, 3,381,022, 3,433,744, 3,444,170, 3,467,668, 3,501,405,3,542,680, 3,576,743, 3,632,511, 4,234,435, Re 26,433, and 6,165,235,7,238,650 and EP Patent Application 0 355 895 A.

The dispersants may also be post-treated by conventional methods by areaction with any of a variety of agents. Among these are boroncompounds (such as boric acid), urea, thiourea, dimercaptothiadiazoles,carbon disulphide, aldehydes, ketones, carboxylic acids such asterephthalic acid, hydrocarbon-substituted succinic anhydrides, maleicanhydride, nitriles, epoxides, and phosphorus compounds. In oneembodiment the post-treated dispersant is borated. In one embodiment thepost-treated dispersant is reacted with dimercaptothiadiazoles. In oneembodiment the post-treated dispersant is reacted with phosphoric orphosphorous acid. In one embodiment the post-treated dispersant isreacted with terephthalic acid and boric acid (as described in US PatentApplication US2009/0054278.

In one embodiment the dispersant may be borated or non-borated.Typically a borated dispersant may be a succinimide dispersant.

The dispersant may be prepared/obtained/obtainable from reaction ofsuccinic anhydride by an “ene” or “thermal” reaction, by what isreferred to as a “direct alkylation process.” The “ene” reactionmechanism and general reaction conditions are summarised in “MaleicAnhydride”, pages, 147-149, Edited by B. C. Trivedi and B. C. Culbertsonand Published by Plenum Press in 1982. The dispersant prepared by aprocess that includes an “ene” reaction may be a polyisobutylenesuccinimide having a carbocyclic ring present on less than 50 mole %, or0 to less than 30 mole %, or 0 to less than 20 mole %, or 0 mole % ofthe dispersant molecules. The “ene” reaction may have a reactiontemperature of 180° C. to less than 300° C., or 200° C. to 250° C., or200° C. to 220° C.

The dispersant may also be obtained/obtainable from a chlorine-assistedprocess, often involving Diels-Alder chemistry, leading to formation ofcarbocyclic linkages. The process is known to a person skilled in theart. The chlorine-assisted process may produce a dispersant that is apolyisobutylene succinimide having a carbocyclic ring present on 50 mole% or more, or 60 to 100 mole % of the dispersant molecules. Both thethermal and chlorine-assisted processes are described in greater detailin U.S. Pat. No. 7,615,521, columns 4-5 and preparative examples A andB.

The dispersant may have a carbonyl to nitrogen ratio (CO:N ratio) of 5:1to 1:10, 2:1 to 1:10, or 2:1 to 1:5, or 2:1 to 1:2. In one embodimentthe dispersant may have a CO:N ratio of 2:1 to 1:10, or 2:1 to 1:5, or2:1 to 1:2, or 1:1.4 to 1:0.6.

The dispersant may be present at 0 wt % to 20 wt %, 0.1 wt % to 15 wt %,or 0.5 wt % to 9 wt %, or 1 wt % to 8.5 wt % of the lubricatingcomposition.

Oils of Lubricating Viscosity

The lubricating composition comprises an oil of lubricating viscosity.Such oils include natural and synthetic oils, oil derived fromhydrocracking, hydrogenation, and hydrofinishing, unrefined, refined,re-refined oils or mixtures thereof. A more detailed description ofunrefined, refined and re-refined oils is provided in InternationalPublication WO2008/147704, paragraphs [0054] to [0056] (a similardisclosure is provided in US Patent Application 2010/197536, see [0072]to [0073]). A more detailed description of natural and syntheticlubricating oils is described in paragraphs [0058] to [0059]respectively of WO2008/147704 (a similar disclosure is provided in USPatent Application 2010/197536, see [0075] to [0076]). Synthetic oilsmay also be produced by Fischer-Tropsch reactions and typically may behydroisomerised Fischer-Tropsch hydrocarbons or waxes. In one embodimentoils may be prepared by a Fischer-Tropsch gas-to-liquid syntheticprocedure as well as other gas-to-liquid oils.

Oils of lubricating viscosity may also be defined as specified in April2008 version of “Appendix E—API Base Oil Interchangeability Guidelinesfor Passenger Car Motor Oils and Diesel Engine Oils”, section 1.3Sub-heading 1.3. “Base Stock Categories”. The API Guidelines are alsosummarised in US Patent U.S. Pat. No. 7,285,516 (see column 11, line 64to column 12, line 10). In one embodiment the oil of lubricatingviscosity may be an API Group II, Group III, Group IV oil, or mixturesthereof.

The amount of the oil of lubricating viscosity present is typically thebalance remaining after subtracting from 100 wt % the sum of the amountof the compound of the invention and the other performance additives.

The lubricating composition may be in the form of a concentrate and/or afully formulated lubricant. If the lubricating composition of theinvention (comprising the additives disclosed herein) is in the form ofa concentrate which may be combined with additional oil to form, inwhole or in part, a finished lubricant), the ratio of the of theseadditives to the oil of lubricating viscosity and/or to diluent oilinclude the ranges of 1:99 to 99:1 by weight, or 80:20 to 10:90 byweight.

Other Performance Additives

A lubricating composition may be prepared by adding the product of theprocess described herein to an oil of lubricating viscosity, optionallyin the presence of other performance additives (as described hereinbelow).

The lubricating composition of the invention optionally comprises otherperformance additives. The other performance additives include at leastone of metal deactivators, viscosity modifiers, detergents, frictionmodifiers, antiwear agents, corrosion inhibitors, dispersant viscositymodifiers, extreme pressure agents, antioxidants, foam inhibitors,demulsifiers, pour point depressants, seal swelling agents and mixturesthereof. Typically, fully-formulated lubricating oil will contain one ormore of these performance additives.

The lubricating composition of the invention may further include otheradditives. In one embodiment the invention provides a lubricatingcomposition further comprising at least one of a dispersant, an antiwearagent, a dispersant viscosity modifier, a friction modifier, a viscositymodifier, an antioxidant, an overbased detergent, or mixtures thereof.In one embodiment the invention provides a lubricating compositionfurther comprising at least one of a polyisobutylene succinimidedispersant, an antiwear agent, a dispersant viscosity modifier, afriction modifier, a viscosity modifier (typically an olefin copolymersuch as an ethylene-propylene copolymer), an antioxidant (includingphenolic and aminic antioxidants), an overbased detergent (includingoverbased sulphonates and phenates), or mixtures thereof.

In one embodiment the lubricating composition may be a lubricatingcomposition further comprising a molybdenum compound. The molybdenumcompound may be an antiwear agent or an antioxidant. The molybdenumcompound may be selected from the group consisting of molybdenumdialkyldithiophosphates, molybdenum dithiocarbamates, amine salts ofmolybdenum compounds, and mixtures thereof. The molybdenum compound mayprovide the lubricating composition with 0 to 1000 ppm, or 5 to 1000ppm, or 10 to 750 ppm 5 ppm to 300 ppm, or 20 ppm to 250 ppm ofmolybdenum.

Antioxidants include sulphurised olefins, diarylamines, alkylateddiarylamines, hindered phenols, molybdenum compounds (such as molybdenumdithiocarbamates), hydroxyl thioethers, or mixtures thereof. In oneembodiment the lubricating composition includes an antioxidant, ormixtures thereof. The antioxidant may be present at 0 wt % to 15 wt %,or 0.1 wt % to 10 wt %, or 0.5 wt % to 5 wt %, or 0.5 wt % to 3 wt %, or0.3 wt % to 1.5 wt % of the lubricating composition.

The diarylamine or alkylated diarylamine may be a phenyl-α-naphthylamine(PANA), an alkylated diphenylamine, or an alkylated phenylnapthylamine,or mixtures thereof. The alkylated diphenylamine may includedi-nonylated diphenylamine, nonyl diphenylamine, octyl diphenylamine,di-octylated diphenylamine, di-decylated diphenylamine, decyldiphenylamine and mixtures thereof. In one embodiment the diphenylaminemay include nonyl diphenylamine, dinonyl diphenylamine, octyldiphenylamine, dioctyl diphenylamine, or mixtures thereof. In oneembodiment the alkylated diphenylamine may include nonyl diphenylamine,or dinonyl diphenylamine. The alkylated diarylamine may include octyl,di-octyl, nonyl, di-nonyl, decyl or di-decyl phenylnapthylamines.

The hindered phenol antioxidant often contains a secondary butyl and/ora tertiary butyl group as a sterically hindering group. The phenol groupmay be further substituted with a hydrocarbyl group (typically linear orbranched alkyl) and/or a bridging group linking to a second aromaticgroup. Examples of suitable hindered phenol antioxidants include2,6-di-tert-butylphenol, 4-methyl-2,6-di-tert-butylphenol,4-ethyl-2,6-di-tert-butylphenol, 4-propyl-2,6-di-tert-butylphenol or4-butyl-2,6-di-tert-butylphenol, or 4-dodecyl-2,6-di-tert-butylphenol.In one embodiment the hindered phenol antioxidant may be an ester andmay include, e.g., Irganox™ L-135 from Ciba. A more detailed descriptionof suitable ester-containing hindered phenol antioxidant chemistry isfound in U.S. Pat. No. 6,559,105.

Examples of molybdenum dithiocarbamates, which may be used as anantioxidant, include commercial materials sold under the trade namessuch as Vanlube 822™ and Molyvan™ A from R. T. Vanderbilt Co., Ltd., andAdeka Sakura-Lube™ S-100, S-165, S-600 and 525, or mixtures thereof.

In one embodiment the lubricating composition further includes aviscosity modifier. The viscosity modifier is known in the art and mayinclude hydrogenated styrene-butadiene rubbers, ethylene-propylenecopolymers, polymethacrylates, polyacrylates, hydrogenatedstyrene-isoprene polymers, hydrogenated diene polymers, polyalkylstyrenes, polyolefins, esters of maleic anhydride-olefin copolymers(such as those described in International Application WO 2010/014655),esters of maleic anhydride-styrene copolymers, or mixtures thereof.

The dispersant viscosity modifier may include functionalisedpolyolefins, for example, ethylene-propylene copolymers that have beenfunctionalised with an acylating agent such as maleic anhydride and anamine; polymethacrylates functionalised with an amine, or styrene-maleicanhydride copolymers reacted with an amine. More detailed description ofdispersant viscosity modifiers are disclosed in InternationalPublication WO2006/015130 or U.S. Pat. Nos. 4,863,623; 6,107,257;6,107,258; 6,117,825; and U.S. Pat. No. 7,790,661. In one embodiment thedispersant viscosity modifier may include those described in U.S. Pat.No. 4,863,623 (see column 2, line 15 to column 3, line 52) or inInternational Publication WO2006/015130 (see page 2, paragraph [0008]and preparative examples are described paragraphs [0065] to [0073]). Inone embodiment the dispersant viscosity modifier may include thosedescribed in U.S. Patent U.S. Pat. No. 7,790,661 column 2, line 48 tocolumn 10, line 38.

In one embodiment the lubricating composition of the invention furthercomprises a dispersant viscosity modifier. The dispersant viscositymodifier may be present at 0 wt % to 5 wt %, or 0 wt % to 4 wt %, or0.05 wt % to 2 wt %, or 0.2 wt % to 1.2 wt % of the lubricatingcomposition.

In one embodiment the invention provides a lubricating compositionfurther comprising an overbased metal-containing detergent. The metal ofthe metal-containing detergent may be zinc, sodium, calcium, barium, ormagnesium. Typically the metal of the metal-containing detergent may besodium, calcium, or magnesium.

The overbased metal-containing detergent may be selected from the groupconsisting of non-sulphur containing phenates, sulphur containingphenates, sulphonates, salixarates, salicylates, and mixtures thereof,or borated equivalents thereof. The overbased detergent may be boratedwith a borating agent such as boric acid.

The overbased metal-containing detergent may also include “hybrid”detergents formed with mixed surfactant systems including phenate and/orsulphonate components, e.g. phenate/salicylates, sulphonate/phenates,sulphonate/salicylates, sulphonates/phenates/salicylates, as described;for example, in U.S. Pat. Nos. 6,429,178; 6,429,179; 6,153,565; and6,281,179. Where, for example, a hybrid sulphonate/phenate detergent isemployed, the hybrid detergent would be considered equivalent to amountsof distinct phenate and sulphonate detergents introducing like amountsof phenate and sulphonate soaps, respectively.

Typically an overbased detergent may be sodium, calcium or magnesiumsalt of the phenates, sulphur containing phenates, sulphonates,salixarates and salicylates. Overbased phenates and salicylatestypically have a total base number of 180 to 450 TBN. Overbasedsulphonates typically have a total base number of 250 to 600, or 300 to500. Overbased detergents are known in the art. In one embodiment thesulphonate detergent may be a linear alkylbenzene sulphonate detergenthaving a metal ratio of at least 8 as is described in paragraphs [0026]to [0037] of US Patent Application 2005065045 (and granted as U.S. Pat.No. 7,407,919). Linear alkyl benzenes may have the benzene ring attachedanywhere on the linear chain, usually at the 2, 3, or 4 position, ormixtures thereof. The linear alkylbenzene sulphonate detergent may beparticularly useful for assisting in improving fuel economy. In oneembodiment the sulphonate detergent may be a metal salt of one or moreoil-soluble alkyl toluene sulphonate compounds as disclosed inparagraphs [0046] to [0053] of US Patent Application 2008/0119378.

Typically the overbased metal-containing detergent may be a calcium ormagnesium an overbased detergent.

Overbased detergents are known in the art. Overbased materials,otherwise referred to as overbased or superbased salts, are generallysingle phase, homogeneous Newtonian systems characterised by a metalcontent in of that which would be present for neutralization accordingto the stoichiometry of the metal and the particular acidic organiccompound reacted with the metal. The overbased materials are prepared byreacting an acidic material (typically an inorganic acid or lowercarboxylic acid, preferably carbon dioxide) with a mixture comprising anacidic organic compound, a reaction medium comprising at least oneinert, organic solvent (mineral oil, naphtha, toluene, xylene, etc.) forsaid acidic organic material, a stoichiometric excess of a metal base,and a promoter such as a calcium chloride, acetic acid, phenol oralcohol. The acidic organic material will normally have a sufficientnumber of carbon atoms to provide a degree of solubility in oil. Theamount of “excess” metal (stoichiometrically) is commonly expressed interms of metal ratio. The term “metal ratio” is the ratio of the totalequivalents of the metal to the equivalents of the acidic organiccompound. A neutral metal salt has a metal ratio of one. A salt having4.5 times as much metal as present in a normal salt will have metalexcess of 3.5 equivalents, or a ratio of 4.5. The term “metal ratio isalso explained in standard textbook entitled “Chemistry and Technologyof Lubricants”, Third Edition, Edited by R. M. Mortier and S. T.Orszulik, Copyright 2010, page 219, sub-heading 7.25.

The overbased detergent (other than the detergent of the presentinvention) may be present at 0 wt % to 15 wt %, or 0.1 wt % to 10 wt %,or 0.2 wt % to 8 wt %, or 0.2 wt % to 3 wt %. For example in a heavyduty diesel engine the detergent may be present at 2 wt % to 3 wt % ofthe lubricating composition. For a passenger car engine the detergentmay be present at 0.2 wt % to 1 wt % of the lubricating composition. Inone embodiment, an engine lubricating composition further comprises atleast one overbased detergent with a metal ratio of at least 3, or atleast 8, or at least 15.

In one embodiment the friction modifier may be selected from the groupconsisting of long chain fatty acid derivatives of amines, long chainfatty esters, or derivatives of long chain fatty epoxides; fattyimidazolines; amine salts of alkylphosphoric acids; fatty alkyltartrates; fatty alkyl tartrimides; fatty alkyl tartramides; fattyglycolates; and fatty glycolamides. The friction modifier may be presentat 0 wt % to 6 wt %, or 0.01 wt % to 4 wt %, or 0.05 wt % to 2 wt %, or0.1 wt % to 2 wt % of the lubricating composition.

As used herein the term “fatty alkyl” or “fatty” in relation to frictionmodifiers means a carbon chain having 10 to 22 carbon atoms, typically astraight carbon chain.

Examples of suitable friction modifiers include long chain fatty acidderivatives of amines, fatty esters, or fatty epoxides; fattyimidazolines such as condensation products of carboxylic acids andpolyalkylene-polyamines; amine salts of alkylphosphoric acids; fattyalkyl tartrates; fatty alkyl tartrimides; fatty alkyl tartramides; fattyphosphonates; fatty phosphites; borated phospholipids, borated fattyepoxides; glycerol esters; borated glycerol esters; fatty amines;alkoxylated fatty amines; borated alkoxylated fatty amines; hydroxyl andpolyhydroxy fatty amines including tertiary hydroxy fatty amines;hydroxy alkyl amides; metal salts of fatty acids; metal salts of alkylsalicylates; fatty oxazolines; fatty ethoxylated alcohols; condensationproducts of carboxylic acids and polyalkylene polyamines; or reactionproducts from fatty carboxylic acids with guanidine, aminoguanidine,urea, or thiourea and salts thereof.

Friction modifiers may also encompass materials such as sulphurisedfatty compounds and olefins, molybdenum dialkyldithiophosphates,molybdenum dithiocarbamates, sunflower oil or soybean oil monoester of apolyol and an aliphatic carboxylic acid.

In one embodiment the friction modifier may be a long chain fatty acidester. In another embodiment the long chain fatty acid ester may be amono-ester and in another embodiment the long chain fatty acid ester maybe a triglyceride.

The lubricating composition optionally further includes at least oneantiwear agent. Examples of suitable antiwear agents include titaniumcompounds, tartrates, tartrimides, oil soluble amine salts of phosphoruscompounds, sulphurised olefins, metal dihydrocarbyldithiophosphates(such as zinc dialkyldithiophosphates), phosphites (such as dibutylphosphite), phosphonates, thiocarbamate-containing compounds, such asthiocarbamate esters, thiocarbamate amides, thiocarbamic ethers,alkylene-coupled thio-carbamates, andbis(S-alkyldithiocarbamyl)disulphides.

The antiwear agent may in one embodiment include a tartrate ortartrimide as disclosed in International Publication WO 2006/044411 orCanadian Patent CA 1 183 125. The tartrate or tartrimide may containalkyl-ester groups, where the sum of carbon atoms on the alkyl groups isat least 8. The antiwear agent may in one embodiment include a citrateas is disclosed in US Patent Application 20050198894.

The lubricating composition may further include a phosphorus-containingantiwear agent. Typically the phosphorus-containing antiwear agent maybe a zinc dialkyldithiophosphate, phosphite, phosphate, phosphonate, andammonium phosphate salts, or mixtures thereof. Zincdialkyldithiophosphates are known in the art. The antiwear agent may bepresent at 0 wt % to 3 wt %, or 0.1 wt % to 1.5 wt %, or 0.5 wt % to 0.9wt % of the lubricating composition.

Another class of additives includes oil-soluble titanium compounds asdisclosed in U.S. Pat. No. 7,727,943 and US2006/0014651. The oil-solubletitanium compounds may function as antiwear agents, friction modifiers,antioxidants, deposit control additives, or more than one of thesefunctions. In one embodiment the oil soluble titanium compound is atitanium (IV) alkoxide. The titanium alkoxide is formed from amonohydric alcohol, a polyol or mixtures thereof. The monohydricalkoxides may have 2 to 16, or 3 to 10 carbon atoms. In one embodiment,the titanium alkoxide is titanium (IV) isopropoxide. In one embodiment,the titanium alkoxide is titanium (IV) 2-ethylhexoxide. In oneembodiment, the titanium compound comprises the alkoxide of a vicinal1,2-diol or polyol. In one embodiment, the 1,2-vicinal diol comprises afatty acid mono-ester of glycerol, often the fatty acid is oleic acid.

In one embodiment, the oil soluble titanium compound is a titaniumcarboxylate. In one embodiment the titanium (IV) carboxylate is titaniumneodecanoate.

Useful corrosion inhibitors for an engine lubricating compositioninclude those described in paragraphs 5 to 8 of WO2006/047486,octylamine octanoate, condensation products of dodecenyl succinic acidor anhydride and a fatty acid such as oleic acid with a polyamine. Inone embodiment the corrosion inhibitors include the Synalox® corrosioninhibitor. The Synalox® corrosion inhibitor may be a homopolymer orcopolymer of propylene oxide. The Synalox® corrosion inhibitor isdescribed in more detail in a product brochure with Form No.118-01453-0702 AMS, published by The Dow Chemical Company. The productbrochure is entitled “SYNALOX Lubricants, High-Performance Polyglycolsfor Demanding Applications.”

Foam inhibitors that may be useful in the compositions of the inventioninclude polysiloxanes, copolymers of ethyl acrylate and2-ethylhexylacrylate and optionally vinyl acetate; demulsifiersincluding fluorinated polysiloxanes, trialkyl phosphates, polyethyleneglycols, polyethylene oxides, polypropylene oxides and (ethyleneoxide-propylene oxide) polymers.

Pour point depressants that may be useful in the compositions of theinvention include polyalphaolefins, esters of maleic anhydride-styrenecopolymers, poly(meth)acrylates, polyacrylates or polyacrylamides.

Demulsifiers include trialkyl phosphates, and various polymers andcopolymers of ethylene glycol, ethylene oxide, propylene oxide, ormixtures thereof.

Metal deactivators include derivatives of benzotriazoles (typicallytolyltriazole), 1,2,4-triazoles, benzimidazoles,2-alkyldithiobenzimidazoles or 2-alkyldithiobenzothiazoles. The metaldeactivators may also be described as corrosion inhibitors.

Seal swell agents include sulpholene derivatives Exxon Necton-37™ (FN1380) and Exxon Mineral Seal Oil™ (FN 3200).

An engine lubricating composition in different embodiments may have acomposition as disclosed in the following table

Embodiments (wt %) Additive A B C Polyester 0.01 to 8  0.1 to 6  0.15 to5  Dispersant   0 to 12  0 to 8 0.5 to 6 Dispersant Viscosity Modifier 0 to 5  0 to 4 0.05 to 2  Overbased Detergent 0.1 to 15 0.1 to 10 0.2to 8 Antioxidant 0.1 to 13 0.1 to 10 0.5 to 5 Antiwear Agent 0.1 to 150.1 to 10 0.3 to 5 Friction Modifier 0.01 to 6  0.05 to 4  0.1 to 2Viscosity Modifier   0 to 10 0.5 to 8    1 to 6 Any Other Performance  0 to 10  0 to 8   0 to 6 Additive Oil of Lubricating Viscosity Balanceto Balance to Balance to 100% 100% 100%

INDUSTRIAL APPLICATION

In one embodiment the invention provides a method of lubricating aninternal combustion engine. The engine components may have a surface ofsteel or aluminium.

An aluminium surface may be derived from an aluminium alloy that may bea eutectic or a hyper-eutectic aluminium alloy (such as those derivedfrom aluminium silicates, aluminium oxides, or other ceramic materials).The aluminium surface may be present on a cylinder bore, cylinder block,or piston ring having an aluminium alloy, or aluminium composite.

The internal combustion engine may or may not have an exhaust gasrecirculation system. The internal combustion engine may be fitted withan emission control system or a turbocharger. Examples of the emissioncontrol system include diesel particulate filters (DPF), or systemsemploying selective catalytic reduction (SCR).

In one embodiment the internal combustion engine may be a diesel fuelledengine (typically a heavy duty diesel engine), a gasoline fuelledengine, a natural gas fuelled engine, a mixed gasoline/alcohol fuelledengine, or a hydrogen fuelled internal combustion engine. In oneembodiment the internal combustion engine may be a diesel fuelled engineand in another embodiment a gasoline fuelled engine. In one embodimentthe internal combustion engine may be a heavy duty diesel engine.

The internal combustion engine may be a 2-stroke or 4-stroke engine.Suitable internal combustion engines include marine diesel engines,aviation piston engines, low-load diesel engines, and automobile andtruck engines. The marine diesel engine may be lubricated with a marinediesel cylinder lubricant (typically in a 2-stroke engine), a system oil(typically in a 2-stroke engine), or a crankcase lubricant (typically ina 4-stroke engine).

The lubricant composition for an internal combustion engine may besuitable for any engine lubricant irrespective of the sulphur,phosphorus or sulphated ash (ASTM D-874) content. The sulphur content ofthe engine oil lubricant may be 1 wt % or less, or 0.8 wt % or less, or0.5 wt % or less, or 0.3 wt % or less. In one embodiment the sulphurcontent may be in the range of 0.001 wt % to 0.5 wt %, or 0.01 wt % to0.3 wt %. The phosphorus content may be 0.2 wt % or less, or 0.12 wt %or less, or 0.1 wt % or less, or 0.085 wt % or less, or 0.08 wt % orless, or even 0.06 wt % or less, 0.055 wt % or less, or 0.05 wt % orless. In one embodiment the phosphorus content may be 0.04 wt % to 0.12wt %. In one embodiment the phosphorus content may be 100 ppm to 1000ppm, or 200 ppm to 600 ppm. The total sulphated ash content may be 0.3wt % to 1.2 wt %, or 0.5 wt % to 1.1 wt % of the lubricatingcomposition. In one embodiment the sulphated ash content may be 0.5 wt %to 1.1 wt % of the lubricating composition.

In one embodiment the lubricating composition may be an engine oil,wherein the lubricating composition may be characterised as having atleast one of (i) a sulphur content of 0.5 wt % or less, (ii) aphosphorus content of 0.12 wt % or less, and (iii) a sulphated ashcontent of 0.5 wt % to 1.1 wt % of the lubricating composition.

The following examples provide illustrations of the invention. Theseexamples are non-exhaustive and are not intended to limit the scope ofthe invention.

EXAMPLES Example 1

Example 1 is a polyester of the current invention. The polyester acid isprepared by reacting 12-hydroxystearic acid in a vessel fitted with astirrer, Dean-Stark trap, sub-surface nitrogen inlet line andthermocouple. The reaction is heated to about 100° C. and zirconiumbutoxide (0.57 wt %) is added and the mixture is heated to about 195° C.for 12 hours. Water is collected in the Dean-Stark trap until the totalacid number is about 30-35 mg KOH/g. The resulting product is cooled andcollected.

A series of engine lubricants are prepared containing the products ofthe examples above.

The engine lubricants include both heavy diesel (HD) and gasolinepassenger car (PC) lubricants. In the lubricant examples below allamounts are expressed on an actives basis.

Comparative Lubricant Example 1 (CLE1) is a passenger car lubricant.CLE1 is an API SM capable 5W-30 lubricant containing 2 wt % of asuccinimide dispersant. The lubricant contains 1.25 wt % of anantioxidant system (containing a mixture of aminic, phenolic andsulphur-containing antioxidants), 0.79 wt % of a zincdialkyldithiophosphate, 0.62 wt % of an ethylene-propylene copolymerviscosity modifier, 0.14 wt % of a pour point depressant, 0.91 wt % of adetergent system (containing a mixture of a sodium overbased sulphonateand calcium overbased sulphonate), 11 ppm of siloxane antifoam agent,and balance API Group II base oil.

Engine Lubricant 1 (EL1): is the same as CLE1 except it further contains3 wt % of Example 1.

The PC compositions (CLE1 and EL1) are tested in a panel cokerapparatus. 210 g of oil to be analysed is placed in a steel sump chamberat 105° C. An agitator consisting of several metal tongs on a spindle isinserted into the sump and spun at 1000 rpm. The apparatus is cappedwith a flat aluminum plate with a constant surface temperature of 325°C. The agitator sprays a continuous thin layer of oil onto the aluminumplate for a period of 4 hours. At the end of test, the plate is removedand optically rated. A rating scale is applied with 0 meaning a platecompletely covered in black deposits and 100 meaning a plate completelyfree of deposits. The results obtained for the test are presented below:

CLE1 EL1 Rating 55 82

The data indicates that adding a polyester of the present inventionincreases the panel coker rating. This means that the addition ofpolyester improves deposit cleanliness.

Comparative Lubricant Example 2 (CLE2) is a heavy duty diesel lubricant.CLE2 is an API CJ-4 capable 15W-40 Lubricant containing 4.1 wt % of asuccinimide dispersant. The lubricant contains 1.23 wt % of anantioxidant system (containing a mixture of aminic, phenolic andsulphur-containing antioxidants), 0.99 wt % of a zincdialkyldithiophosphate, 1.24 wt % of an ethylene-propylene copolymerviscosity modifier, 0.08 wt % of pour point depressant, 1.71 wt % of adetergent system (containing a mixture of a calcium overbased sulphonateand calcium overbased sulphonate), 100 ppm of siloxane antifoam agent,0.12 wt % of corrosion inhibitor, and balance API Group II base oil.

Engine Lubricant 2 (EL2): is the same as CLE2 except it further contains3 wt % of Example 1.

Engine Lubricant 3 (EL3): is the same as CLE2 except it contains only2.1 wt % of a succinimide dispersant and 2.1 wt % of Example 1.

Engine Lubricant 4 (EL4): is the same as CLE2 except it contains nosuccinimide dispersant and 4.1 wt % Example 1.

CLE2 and EL2 to EL4 are evaluated by panel coker test as describedabove. The results obtained for the heavy duty diesel lubricants are asfollows:

CLE2 EL2 EL3 EL4 Rating 46 60 58 9

The data indicates that adding a polyester of the present inventionincreases the panel coker rating. This means that the addition ofpolyester improves deposit cleanliness. The data further indicates thatwhen the inventive polyester is used in combination with a succinimidedispersant as in EL2 and EL3, coker ratings were far superior to whenthe polyester was used alone as in EL4. Thus, the polyester of theinvention works synergistically with succinimide dispersants to improvecoker panel deposits.

It is known that some of the materials described above may interact inthe final formulation, so that the components of the final formulationmay be different from those that are initially added. The productsformed thereby, including the products formed upon employing lubricantcomposition of the present invention in its intended use, may not besusceptible of easy description. Nevertheless, all such modificationsand reaction products are included within the scope of the presentinvention; the present invention encompasses lubricant compositionprepared by admixing the components described above.

Each of the documents referred to above is incorporated herein byreference. Except in the Examples, or where otherwise explicitlyindicated, all numerical quantities in this description specifyingamounts of materials, reaction conditions, molecular weights, number ofcarbon atoms, and the like, are to be understood as modified by the word“about.” Unless otherwise indicated, each chemical or compositionreferred to herein should be interpreted as being a commercial gradematerial which may contain the isomers, by-products, derivatives, andother such materials which are normally understood to be present in thecommercial grade. However, the amount of each chemical component ispresented exclusive of any solvent or diluent oil, which may becustomarily present in the commercial material, unless otherwiseindicated. It is to be understood that the upper and lower amount,range, and ratio limits set forth herein may be independently combined.Similarly, the ranges and amounts for each element of the invention maybe used together with ranges or amounts for any of the other elements.

As used herein, the term “hydrocarbyl substituent” or “hydrocarbylgroup” is used in its ordinary sense, which is well-known to thoseskilled in the art. Specifically, it refers to a group having a carbonatom directly attached to the remainder of the molecule and havingpredominantly hydrocarbon character.

Examples of hydrocarbyl groups include: hydrocarbon substituents,including aliphatic, alicyclic, and aromatic substituents; substitutedhydrocarbon substituents, that is, substituents containingnon-hydrocarbon groups which, in the context of this invention, do notalter the predominantly hydrocarbon nature of the substituent; andhetero substituents, that is, substituents which similarly have apredominantly hydrocarbon character but contain other than carbon in aring or chain. A more detailed definition of the term “hydrocarbylsubstituent” or “hydrocarbyl group” is described in paragraphs [0118] to[0119] of International Publication WO2008147704, or a similardefinition in paragraphs [0137] to [0141] of published application US2010-0197536.

While the invention has been explained in relation to its preferredembodiments, it is to be understood that various modifications thereofwill become apparent to those skilled in the art upon reading thespecification. Therefore, it is to be understood that the inventiondisclosed herein is intended to cover such modifications as fall withinthe scope of the appended claims.

What is claimed is:
 1. A lubricating composition comprising: an oil oflubricating viscosity, 0.05 wt % to 10 wt % of a polyester whichcomprises a self-condensation product of a C₈₋₂₂ fatty carboxylic acidcontaining at least one hydroxyl group, 0.1 wt % to 15 wt % of adispersant, and 0.1 wt % to 10 wt % of an overbased calcium- ormagnesium-containing detergent.
 2. The lubricating composition of claim1, wherein the fatty carboxylic acid is represented by the formula:

where R¹ is a hydrogen or a hydrocarbyl group containing from 1 to 20carbon atoms and R² is a hydrocarbylene group containing from 1 to 20carbon atoms, with the proviso that the total number of carbon atomspresent from R¹ and R² is 6 or more.
 3. The lubricating composition ofclaim 1, wherein the self-condensation product of the C₈₋₂₂ fattycarboxylic acid containing at least one hydroxyl group produces apolyester with 2 to 10 repeat units.
 4. The lubricating composition ofclaim 1, wherein the polyester is present at 1 wt % to 8 wt % of thelubricating composition.
 5. The lubricating composition of claim 1,wherein the dispersant is a succinimide dispersant or mixtures thereof.6. The lubricating composition of claim 1, wherein the dispersant is apolyisobutylene succinimide, wherein the polyisobutylene from which thepolyisobutylene succinimide is derived has a number average molecularweight in the range of 750 to
 2200. 7. The lubricating composition ofclaim 1, wherein the dispersant is a polyisobutylene succinimide derivedfrom an aliphatic polyamine selected from the group consisting ofethylenediamine, diethylenetriamine, triethylenetetramine,tetraethylenepentamine, pentaethylenehexamine, polyamine still bottoms,and mixtures thereof.
 8. The lubricating composition of claim 1, whereinthe dispersant is a polyisobutylene succinimide derived from analiphatic polyamine selected from tetraethylenepentamine,pentaethylenehexamine, polyamine still bottoms, and mixtures thereof. 9.The lubricating composition of claim 1, wherein the dispersant is apolyisobutylene succinimide having a carbocyclic ring present on lessthan 50 mole % of the dispersant molecules.
 10. The lubricatingcomposition of claim 1, wherein the dispersant is a polyisobutylenesuccinimide having a carbocyclic ring present on 50 mole % or more ofthe dispersant molecules.
 11. The lubricating composition of claim 1,wherein the dispersant is present at 1 wt % to 8.5 wt % of thelubricating composition.
 12. A method of lubricating an internalcombustion engine comprising supplying to the internal combustion enginea lubricating composition of claim
 1. 13. The method of claim 12,wherein the internal combustion engine has a steel surface on a cylinderbore, cylinder block, or piston ring.
 14. The method of claim 12,wherein the internal combustion engine has a surface of steel, or analuminium alloy, or an aluminium composite.